We want to understand how combustion processes produce mutagens and how to minimize their escape into the atmosphere. For the past ten years, combustion engineers, analytical chemists and toxicologists in this program have focussed on the polycyclic aromatic hydrocarbons formed and incompletely destroyed in flame processes in a number of experimental and practical combustors. We have, in a number of instances, been able to ascribe the preponderance of biological activity in experimental assay systems to one of a few effluent components. Because the PAH alone have been found to account for only part of the biological activity observed, we propose now to extend our scope to the identification of the oxygen and nitrogen-containing aromatics to which we attribute this additional activity and also to their formation through partial oxidation and pyrolysis. These present new, challenging problems to engineers, analytical chemists and toxicologists. The biological endpoints upon which we rely to nominate compounds for further study will continue to be gene mutation in bacteria and human cells as well as induction of lung adenomas in the infant mouse. We also want to discover if present combustion emission components are actually entering humans and causing biological damage. Thus, a major new component in our program is a proposal to study the process of biological damage by combustion-related mutagens and carcinogens using newly developed analytical tools which are intended for eventual use in human population studies. Using compounds such as fluoranthene, a major contributor to PAH activity in nearly all effluents studied to date, we propose to measure the temporal cascade of formation of protein and DNA covalent adducts, the appearance of specific sets of mutations (human B cells) and the appearance of both mutations and lung adenomas in mice. Our program is thus a characterization of two processes of mass transfer: - fuel to mutagens in exhaust - exhaust mutagens through macromolecular reaction products to stable genetic change and cancer.